Pituitary gland (English)

The adenohypophysis is derived from an outpouching of the roof of the oral cavity and is comprised of three parts: the pars distalis (anterior or glandular part), the pars tuberalis (infundibular part) and the pars intermedia. The pars distalis is the largest part and is responsible for most of the secretory activity. The pars tuberalis is a posterior extension of the anterior lobe that surrounds the infundibular stalk, while the pars intermedia is located between the pars distalis of the adenohypophysis and the neurohypophysis. A small cleft is generally apparent between the pars distalis and intermedia. The neurohypophysis is a diencephalic structure and is essentially an extension of the hypothalamus. It can be divided into two main parts. The superior portion is continuous with the median eminence of the hypothalamus and is known as the infundibular stalk. It is comprised of thousands of unmyelinated hypothalamohypophyseal axons. The lower, larger portion of the neurohypophysis belongs to the pars nervosa (neural lobe); it mainly consists of the terminal endings of hypothalamohypophyseal neurons.